Effects of different dietary lipid levels on physiological metabolism and odor quality of hepatopancreas in adult female Chinese mitten crab (Eriocheir sinensis)

This study aimed to investigate the impact of different dietary lipid levels on the physiological metabolism and odor quality of adult female Eriocheir sinensis during the fattening phase. Five dietary schemes, each containing different total lipid levels (4%, 7%, 10%, 13%, and 16%) were administered over a 60-day fattening period for adult female crab (approximately 50 g, n = 60). Dietary lipids had no significant effect on growth performance and hepatopancreas index (P < 0.05). The carotenoid content showed an increasing and then decreasing trend, with a significant increase to 1312.51 mg/kg (P < 0.05) at 7% lipid content of the diet. In contrast, a diet with a 13% lipid level led to a significant increase in total unsaturated fatty acids (115.3 mg/g, P < 0.05), which maximized the contents of major fatty acids (oleic, linoleic, and linolenic, among others), and present a fluctuating trend. A diet with higher lipid levels (16%) inhibited fatty acid accumulation. Moreover, a 13% dietary lipid level enhanced characteristic aroma compounds (e.g., nonanal, octanal, hexanal, 3-methylbutanal, 2-heptanone, among others) in E. sinensis cooked hepatopancreas. Through an orthogonal partial least squares discriminant analysis (OPLS-DA) model, it becomes evident that lipids and carotenoids together promote aroma formation in hepatopancreas. Based on the current findings, the optimal dietary lipid level for enhancing the odor quality of hepatopancreas in adult female E. sinensis during the fattening phase was 13%. This study provides more precise options for the high-quality cultivation of E. sinensis.